Magnetic properties of copper(II) complexes containing peptides. Crystal structure of [Cu(phe-leu)]

A novel copper(II) complex containing the peptide phe-leu has been prepared and characterized. The crystal structure of [Cu(pheleu)] (1) was determined by X-ray diffraction. The presence of carboxylate and amido bridges allows the formation of an extended 2D arrangement. This structure is similar to those found in [Cu(gly-val)]center dot 1/2H(2)O (2), [Cu(val-gly)] (3), [Cu(val-phe)] (4), and [Cu(phe-phe)] (5). The magnetic properties of compounds 1-5 were studied and analyzed comparatively. The experimental data show that the magnetic interactions are mainly transmitted through mu(2)-COO(-) bridges, being ferromagnetic for 1 and 3, and antiferromagnetic for 2, 4 and 5. (c) 2006 Elsevier B.V. All rights reserved.